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Commit146c301

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refactor 109
1 parent63c6c59 commit146c301

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2 files changed

+58
-17
lines changed

2 files changed

+58
-17
lines changed

‎src/main/java/com/fishercoder/solutions/_109.java

Lines changed: 22 additions & 17 deletions
Original file line numberDiff line numberDiff line change
@@ -4,29 +4,34 @@
44
importcom.fishercoder.common.classes.TreeNode;
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/**
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* 109. Convert Sorted List to Binary Search Tree
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*
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* Given a singly linked list where elements are sorted in ascending order, convert it to a height balanced BST.
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*/
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publicclass_109 {
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publicTreeNodesortedListToBST(ListNodehead) {
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returnrec(head,null);
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}
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publicstaticclassSolution1 {
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publicTreeNoderec(ListNodestart,ListNodeend) {
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if (start ==end) {
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returnnull;
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}else {
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ListNodemid =start;
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ListNodeprobe =start;
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while (probe !=end &&probe.next !=end) {
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mid =mid.next;
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probe =probe.next.next;
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}
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publicTreeNodesortedListToBST(ListNodehead) {
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returntoBstRecursively(head,null);
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}
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TreeNoderoot =newTreeNode(mid.val);
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root.left =rec(start,mid);
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root.right =rec(mid.next,end);
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returnroot;
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publicTreeNodetoBstRecursively(ListNodestart,ListNodeend) {
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if (start ==end) {
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returnnull;
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}else {
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ListNodemid =start;
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ListNodefast =start;
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while (fast !=end &&fast.next !=end) {
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mid =mid.next;
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fast =fast.next.next;
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}
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TreeNoderoot =newTreeNode(mid.val);
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root.left =toBstRecursively(start,mid);
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root.right =toBstRecursively(mid.next,end);
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returnroot;
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}
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}
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}
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Lines changed: 36 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,36 @@
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packagecom.fishercoder;
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importcom.fishercoder.common.classes.ListNode;
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importcom.fishercoder.common.classes.TreeNode;
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importcom.fishercoder.common.utils.LinkedListUtils;
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importcom.fishercoder.common.utils.TreeUtils;
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importcom.fishercoder.solutions._109;
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importorg.junit.Before;
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importorg.junit.BeforeClass;
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importorg.junit.Test;
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importjava.util.Arrays;
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publicclass_109Test {
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privatestatic_109.Solution1solution1;
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privatestaticListNodehead;
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privatestaticTreeNodeexpected;
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@BeforeClass
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publicstaticvoidsetup() {
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solution1 =new_109.Solution1();
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}
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@Before
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publicvoidsetUp()throwsException {
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}
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@Test
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publicvoidtest1() {
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head =LinkedListUtils.contructLinkedList(newint[]{1,2,3,4,5});
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expected =TreeUtils.constructBinaryTree(Arrays.asList(3,1,4,null,2,null,5));
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/**as long as it's a height-balanced tree, it's good for this problem requirement*/
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TreeUtils.printBinaryTree(solution1.sortedListToBST(head));
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}
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}

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